Density is defined as mass divided by volume.

• A. Mass/Volume
• B. Volume/Mass
• C. Mass X Gravity
• D. Mass X Velocity/Time

Answer: (A)

Density measures how much matter is packed into a given amount of space. It is defined as mass divided by volume, so density equals mass per unit volume. This means if you keep the mass the same but increase the volume, density falls; if you increase the mass while keeping volume the same, density rises. For example, 2 kg of material occupying 1 liter has a density of 2 kg/L; the same 2 kg occupying 4 liters would have 0.5 kg/L. Common units are kg/m^3 or g/cm^3.

Other expressions don’t describe density: reversing the order to volume per mass gives the inverse quantity; multiplying mass by gravity gives weight; multiplying mass by velocity and then dividing by time relates to momentum rate, not density.